This invention has to do with methods and apparatus for cutting large blocks of cheese into portions, e.g. for packaging.
Various automated systems exist for doing this. A manufactured block of cheesexe2x80x94usually rectangular and weighing for example 20 kg, or 640 lb in the US, xe2x80x94has to be divided into portions whose weight and shape generally need to be selected according to various criteria depending on the type of cheese, the end user, prevailing commercial regulations and so forth.
Issues of practical significance in an automated system include the following (not necessarily all together):
that the system will cut up a large number of blocks without failing, jamming or damaging the cheese;
that the system is sufficiently versatile to be able to cut to different geometries according to the end use and other criteria;
that the system presents the cut portions separated from or easily separable from one another so that they can conveniently be presented to a packaging machine;
that the system can cut to satisfy a target weight criterion for the portions, e.g. by cutting to maintain an average portion weight and deviation from the average within set limits, with reliability and low wastage;
that the system be as compact as possible on the factory floor, and fast and convenient to operate, maintain and adjust.
These are difficult things to achieve, particularly in combination, not least because cheese is in itself a difficult product to handle and furthermore because typically the original large blocks vary significantly from one another (in shape, weight, density and dimensions) and these variations need to be accommodated by the cutting system.
By way of introduction, the operation of a sophisticated known system (our own Wright Pugson C33) is shown schematically in FIG. 1. The incoming cheese block 1 of height H width W and length L is presented at a weighing and centring station where it is aligned, weighed and its width W and height H measured. These data are input to a control processor CP programmed to determine a suitable cut geometry, at least for the vertical-longitudinal (vl1,2) and horizontal (h1) i.e. depth cuts. The program is operable according to various operator requirements. One important regime operates with a view to forming the largest possible number of portions in a predetermined target weight range, maintaining a required average weight and with minimum wastage. The control processor CP is therefore connected to control the cut geometry by adjusting the spacing of cutter elements (metal wires or blades set in a frame) in first-stage and second-stage cutting stations 6xe2x80x2, 7xe2x80x2 which respectively form the horizontal (depth) and vertical-longitudinal cuts by the block""s being pushed through the frame. FIG. 1 shows a version in which the first- and second-stage cutter frames are combined at a single cutting station; they may alternatively be positioned at a spacing. The block, now cut into two layers 11xe2x80x2 each made up of longitudinal sticks 12xe2x80x2, issues onto a turntable (not shown) where it is rotated through 90xc2x0 (as described in our GB-A-2225929). Its width (the original length dimension L) is measured and the cutter spacing of a third-stage cutting station 8xe2x80x2 adjusted accordingly using the L data together with the weight M and the H and W data gathered previously. The block is then pushed, either as a whole or one layer 11xe2x80x2 at a time, through the third-stage cutting station 8xe2x80x2 to form the eventual portions 13. The fully-cut block of portions 13 is then dismantled and the portions loaded onto a packing machine either manually or by an automated procedure; see for example our GB-A-2285962.
Our new proposals relate to apparatus and methods for cutting cheese blocks into portions, including
(a) optionally, making one or more longitudinal cuts to divide the width of the block;
(b) making plural transverse cuts to divide the length of the block, and
(c) optionally, making one or more longitudinal cuts to divide the depth of the block. Usually, at least one and preferably both kinds of longitudinal cut will be made, or at least is/are available to be made.
In a first aspect a longitudinal cutting stage, including making the one or more longitudinal cuts (a) and/or (c) to form a set of longitudinal sticks, is followed by a transverse cutting stage in which the longitudinal sticks are presented together as a set at a transverse cutting station. At the transverse cutting station the transverse cuts (b) are preferably made through the set, forming with each transverse cut a corresponding set of portions. Additionally or alternatively, different sticks of the set may be subjected to different transverse cutting.
A first particular proposal in relation to this aspect is that the transverse cuts be made successively, so as to form sets of portions successively, and separating the successively-formed sets of portions from the residue of the set of sticks. This enables a high rate of formation of portions while moving them progressively downstream in the process. Difficulties in handling and dismantling large fully-cut blocks or part-blocks are thereby reduced or avoided. The sets of portions may be fed successively to the intake of a packaging machine via apparatus for portion orientation and spacing.
The transverse cutting station preferably includes a set separation arrangement which for the making of a transverse cut also moves a respective cut set of portions downstream in the process away from the residue of the set of sticks. For example the cut sets of portions may be on, or be urged or fall onto, a separate conveyor to carry them successively downstream.
The set of sticks is desirably presented unseparated for the transverse cutting, i.e. with the sticks abutting side-by-side along the longitudinal cut(s). This can maximise speed. It is strongly preferred that only one set of sticks be transversely cut at a time, i.e. as a single xe2x80x9clayerxe2x80x9d. Thus, where a cut (c) is made to divide the depth of the block this is preferably done before the transverse cuts (b), preferably also before the longitudinal cut(s) (a), and the resulting layers separated from one another before the transverse cuts are made in each. They may conveniently separate at the longitudinal cutting stage; this is in itself well-known.
It should be noted however that the system may allow for xe2x80x9csetsxe2x80x9d of only one stick e.g. if it is chosen to make no longitudinal cuts in a given block, or longitudinal cuts in only one sense to create layers which are separated before the transverse cutting.
The direction of the transverse cuts is preferably transverse in space to the longitudinal cutting direction, i.e. the set of sticks is not rotated between the longitudinal and transverse cutting stages.
A convenient and compact arrangement makes the transverse cuts with a cutting movement in the depth direction of the set of sticks, preferably cutting all sticks of the set simultaneously, and/or with an active (driven) cutter element such as a guillotine cutter. An active (e.g. guillotine) cutter is usually stronger and easier to control and maintain than cutter elements in a frame, and well suited to making single successive cuts. Furthermore an indexing conveyor is conveniently used to space the transverse cuts by moving the set of sticks progressively longitudinally relative to the cutter location between cuts. This is much more convenient and can be done with simpler apparatus than is required to control the spacing of a set of cutter elements adapted to make plural cuts simultaneously.
By these means the cutting operation may if wished be done in-line, i.e. from the initial block to a separated set of portions without requiring transverse movements or rotations of the cheese. A straight line is preferred.
The cutting methodology and systems described above are in themselves new and advantageous for the reasons given. Normally it will be desired also to be able to adjust the cut geometry (i.e. the spacing and/or position of cuts in any or all of the three dimensions) not only as part of a pre-operational set up but also as an ongoing matter during operation to take into account variations from one block to another. For example, the user might wish to ensure that each block is cut into the same number of equally-sized portions irrespective of variation in block dimensions, so that there is no wastage. Or, more commonly, there may be a requirement to maintain a weight standard for the portions to a predetermined level of strictness in terms of average and deviation, while nevertheless minimising wastage arising from unavoidable creation of underweight residues.
Therefore it is preferred to measure the length and/or weight for each set of sticks and to determine the spacing of the transverse cuts in dependence on those data. In terms of apparatus, this is provided by means for measuring those parameters, and a control processor adapted to receive the length and/or weight data, programmed to determine a corresponding transverse cut spacing on the selected basis, and connected to cause the transverse cutting station to operate at the determined spacing in making the transverse cuts on that set.
While the simultaneous cutting of a set of sticks can radically enhance the speed of portion production without rushing the operation of the transverse cutter, it will be noted that if a single cutter element is used then all sticks of the set will be subject to the same transverse cut spacing. A possible refinement is to use a transverse cutter arrangement adapted to discriminate between sticks of a set and cut them differently.
In particular, however, to further reduce the possibility of wastage in these circumstances, we propose the following preferred feature. In addition to the measurements referred to above for the set of sticks, the width and/or depth, (preferably both) dimensions of the block are also measured, and the block weight too if portion weight is to be controlled. These measured data are fed to the control processor which uses them to determine the cut geometry for the block for the cuts (a), (b) and (c)xe2x80x94(a) and/or (c) being optionalxe2x80x94so as best to satisfy the operational requirements (e.g. target weight, shape restrictions etc.). It should be noted that the principles for programming a control processor to determine a cut geometry can be in themselves generally routine programming and furthermore may be similar to the principles implemented in our known C33 system referred to above.
By this means it becomes possible to control better the shape and size of the longitudinal sticks in dependence on the dimensions of the incoming block, taking into account that the sticks of a given set will be cut together and thereby offsetting a relative lack of flexibility and possible additional wastage which might otherwise result at that stage.
The dimensional and weight data referred to need not all be gathered initially, although they may all be measured on the incoming uncut block. They may additionally or alternatively be measured in turn as they are required for determining cut spacing. Thus for example generally a block dimension will need to be measured before a cutting stage which cuts transverse to that dimension.
Weight and dimensions may be measured by conventional means, for example load cells, mechanical devices using linear or radial transducers, optical devices with analogue outputs etc. Cut spacings may also be controlled by known means. The spacing of plural cutter elements in a cutting arrangementxe2x80x94usually a passive cutter arrangement such as a frame spanned by cutter elementsxe2x80x94may be adjusted via a geared electromechanical coupling controlled from the control processor. The spacing of cuts made by a single, e.g. active, cutter may be adjustedxe2x80x94usually more simply and convenientlyxe2x80x94by using the control processor to govern the indexing movements of an indexing conveyor which effects relative movement between the cutter and the cheese between cuts.
A further and independent proposal herein, but preferably combined with the specific proposals above relating to sequential transverse cutting of sets, relates to methods and apparatus by which the control processor is used to determine the cut geometry for a given block based on dimensional and/or weight parameters of that block e.g. in a manner described above. Our second proposal relates to systems in which the control processor enables determination of cut geometries to create portions which do not deviate beyond a specified limit above or below a target weight, and which average the target weight. Such processor programming is in itself known.
What we propose is that the control processor bases the cut geometry for a given incoming block not only on the parameters for that block e.g. as aforesaid, but additionally on portion weight parameters determined for one or more other blocks of a series of blocks being cut whose cut geometries, and hence portion weight distribution, have already been determined. For maximum reliability this is best done by actual measurement of the portion weights of portions which have already been cut, feeding accumulated weight data for already-cut portions back to the control processor which determines the cut geometry for subsequent blocks. These portion weight data are then used together with the dimensional and weight data of each incoming block in determining the cut geometry to be applied to the incoming block.
The benefit here is as follows. The control processor is programmed to determine a cut geometry that satisfies predetermined average weight and weight variation restrictions, while minimising wastage. In previous systems this has been done for each block in turn. However by feeding portion weight data from other blocks into the cut geometry determination for a given block, it becomes possible to ensure that the portion weight average is maintained over a number (greater than 1) of blocks, without its necessarily having to be maintained for a given block in isolation. Thus in particular the control processor may be programmed to select a cut geometry for a given block that will divide the block into portions which fall within the permitted limits of portion weight variation, but do not satisfy the portion weight average criterion, because the portion weight average criterion can be satisfied over a larger number of blocks by an opposite deviation from that criterion determined in portions created from other blocks, e.g. which have already been cut.